As the article points out, we've come a long way. When I was a child in the 1970s, a visit to the city meant a headache, burning sensations in the eyes, and a sulfurous taint to the air. On bad days we'd have smog alerts inland and in the city, occasionally bad enough that the authorities would tell you not to exercise or breathe very much at all, thanks.
Dissatisfaction with this state of affairs led to legislation, and since California is a huge market for automobiles the automakers and oil companies had to cave. Over the last 30 years emissions from vehicles have dramatically reduced. You don't get a sick headache from a summer day in Los Angeles any more, and smog alerts are rare. The ruthless Air Quality people crack down on generators, drive through restaurants, even barbecues to keep particulate matter and ozone out of the air.
It turns out that further improvement may be a lot harder. We're still stuck with the inversion layer that keeps everything squeezed down on top of Los Angeles. There was smog before cars because of this; the Spanish called the Santa Monica Bay the "Bay of Smokes" because it was so hazy from forest fire smog.
And the last big set of air polluters are beyond our reach. The Ports of Los Angeles and Long Beach are gigantic and essential to the nation, and they spew the worst possible diesel fumes. Locomotives, idling trucks, and ships are all egregious polluters and for various reasons are beyond the regulatory authority of the State. Locomotives are regulated by the federal EPA, for example, and ships by an International Maritime Organization. The U.S. hasn't ratified the maritime treaty that would somewhat improve our ability to regulate marine pollution. The EPA says that locomotive fuel will become cleaner over five years starting in 2007. And diesel standards for trucks are progressively improving, but only for new engines, leaving an installed base of dirty engines that will be used until they finally die.
Unsurprisingly, shipowners and trucking company bosses are not enthusiastic about upgrading their fuel and engines. So it looks like we're stuck paying a huge price for the nation's import-export economy for at least another 20-30 years.
Once again I'm glad I live by the ocean, where the smog never comes.